An analysis of normal finger force was performed by the technique of optimization. A graphical method was utilized to present the results for a better understanding of the redundant force analysis problem. Normative models for the fingers were developed to perform simulation studies of abnormal hand conditions. Accurate instruments were fabricated and tested for patient evaluation. Important data have been produced. The present extension of the project attempts to: 1) Expand the study to analyze normal and abnormal thumb forces. 2) Determine capsuloligamentous forces of the joint. 3) Analyze the pathomechanics of finger and thumb deformity by simulation studies. 4) Perform objective patient evaluation. 5) Obtain qualitative validation of the analytical results based on quantitative EMG analysis. Normative thumb model will be developed following the same technique applied to the fingers. An optimization method will be used for solution of the thumb and for the analysis of abnormal forces. When the muscle strength is reduced due to pathological conditions, the functional forces will be calculated in a reversed manner by treating the external applied force as an additional unknown. Detailed cross-sectional studies will be performed to construct the capsuloligamentous model and its force components will be determined by equipollent force analysis technique. Cadaver finger specimens will be tested under bending and torsion to assess the role of the ligaments and capsule in maintaining joint stability. Patients with pathological conditions will be evaluated biomechanically. Integrated EMG of extrinsic and intrinsic muscles will be measured while the hand is performing isometric functions. These values will be correlated with theoretically predicted forces for qualitative comparison.